1. Field of the Invention
The invention relates to techniques for applying adhesive to portions of cardboard blanks which thereafter can be folded and compressed to form cardboard boxes.
2. Description of the Prior Art
Cardboard boxes typically are formed by slotting and scoring rectangular pieces of cardboard to form so-called blanks. The blanks are folded appropriately and "stitched," either by gluing or stapling, to form completed boxes.
Machinery suitable for forming cardboard boxes has been known for some time. An example is the patent to Dormandy, U.S. Pat. No. 1,067,867. Dormandy discloses a gluing machine which operates upon prescored blanks having four sides and a lap, or edge section. The blanks are passed through a machine where they are folded such that a portion of the blanks extends downwardly through a longitudinally extending slot formed in a flat bed. The lap is positioned at approximately the center of the machine, passing over a narrow glue wheel where glue is applied to the lap portion. The now-glued lap passes over a depression in the bed. A curved slot and a curved board cause the downwardly extending portion of the blank to be brought into contact with the underside of the remaining portion of the box such that the lap contacts the edge portion of the box. The folded box is compressed between rolls so as to complete the stitching operation.
Another machine suitable for forming cardboard boxes is disclosed in the patent to Phin et al., U.S. Pat. No. 2,859,727. A preslotted, prescored blank is folded over a mandrel and is forced into a box-like tunnel defined by bottom plates, side plates, and top plates. During their passage through the tunnel, the end portions of the blank receive glue from gluing devices. The end portions are folded inwardly, and other end portions are folded down into contact with the glued portions. Pressure then is applied to the folded end portions to set the adhesive.
Although devices such as those disclosed in the Dormandy and Phin patents are effective for the purpose of forming completed or substantially completed cardboard boxes, they do not address the problem of applying adhesive to cardboard boxes which are supplied to customers in knocked-down form for subsequent assembly. It often is important to be able to store a number of boxes in knocked-down form, the boxes being assembled only when they are needed. A particular industry where such a practice is carried out is the moving industry. Typically, hundreds of boxes will be supplied to a given customer in knocked-down condition. In this condition, the boxes can be stored compactly until they are needed, whereupon the boxes can be assembled.
A typical so-called moving box consists of a prescored, preslotted cardboard blank which is folded in half and "stitched" along one edge, usually by means of adhesive or staples. Upon opening a box and folding preformed flaps inwardly, a completed box will be formed. The flaps can be secured to each other by means of adhesive, staples, or tape. Moving boxes can be supplied with both top and bottom flaps, or they can be supplied with only bottom flaps, in which case a separate cover can be provided.
A particularly desirable type of moving box is one in which pressure-sensitive adhesive is applied to the flaps at the factory prior to shipment to customers. These boxes are particularly desirable because they can be assembled very quickly and easily. Unfortunately, the cost of the adhesive and the cost of applying it makes these boxes more expensive than boxes not so treated.
Known techniques for applying pressure-sensitive adhesive to the flaps of cardboard boxes are either inefficient or too expensive. The adhesive usually is applied manually by means of a paint roller, a paint brush, or by spraying. Production rates are low and labor costs are high. Although a technique for applying adhesive by machine is known, the machine in question is an expensive, converted printing press that performs a number of operations on the cardboard blanks. The expense of the machine is such that it cannot be acquired by many manufacturers of cardboard boxes. Desirably, a technique would be available that would enable boxes such as moving boxes to be treated with pressure-sensitive adhesive and yet would keep the cost of the boxes competitive with other types of boxes not so treated.